Anti-Arrythmics

Question 1

Vaugh Williams Classification of Class 1A action drug

Answer 1

Block of Na+ channels - Action: slowed conduction velocity

Question 2

Class 2 Action drug

Answer 2

Block B-receptors - Anti-adrenergic action NE,E

Question 3

Class 3 Action drug

Answer 3

Block K+ channel - prolong action potential duration and refractoriness

Question 4

Class 4 Action drug

Answer 4

Block Ca+ channel - Heart rate slowing, slowing AV node conduction

Question 5

Class 1 Na Channel blockers A.

Answer 5

Intermediate Kinetics - A. Quinidine, Procainimide
INcrease QRS
INcrease QT
Makes them also class 3 - prolonging action potential duration

Question 6

Class 1 Na Channel blockers B.

Answer 6

Fast Kinetics - B. Lidocaine, Mexilitene

SHorter QT

Question 7

Class 1 Na Channel blockers C.

Answer 7

Long Kinetics
C. Propafenone, Flecainide
Last on Na channel for 3-5 s - drug effect increases with more heart beats - MORE POTENT at rapid heart rates
INcrease QRS

Question 8

K channel blocker class?

Answer 8

Class 3.
Amiodarone (most common, all class actions, mostly K+ channel block),
Sotalol, Dronedarone, Dofetilide

Question 9

Ca channel blocker

Answer 9

Dilitiazem, Verapamil (blocks efflux of hoecst 33342) - inhibitor of Pgp

Question 10

Other anti-arrhythmic agents

Answer 10

Digitalis
Slowing agents - Ivabradine
Atrial selective drugs - Ikur, IKAch blockers

Question 11

Blocking k+ channels mechanisms

Answer 11

Block K+ channels, prolong the action potential duration
Prolongs refractory period
makes re-entry less likely

Question 12

Quinidine - mechanism of action

Answer 12

Na channel blocker (1A)
And
K channel blocker

Question 13

Flecainide - mechanism of action

Answer 13

Na channel blocker (1C)
AND
Ryanidine receptor blocker RYR2
AND some 
K channel blocker

Question 14

Drugs for reentry and class 3 effects

Answer 14

Slow refractory period - WORKS

Slowed conduction - INCREASES chance of reentry (e.g. propafanone and flecainide) - dying patients

Question 15

When do we use antiarrhythmic agents?

Answer 15

1. Atrial fibrillation /flutter/tachycardia
2. Ventricular arrhythmia/tachycardias - scar from MI
3. Ventricular fibrillation - Cardiac arrests - ET. Bretylium (class 3)

Question 16

Risks of Anti-arrhythmics

Answer 16

1 Sudden death (na+ channel blocker)

2. Fatigue, Bradycardia (b blockers)
3. Torsade de Pointes VT, sudden death
4. worsening heart failure, bradycardia

Question 17

What does fleicanide cause

Answer 17

pro-arrythmias